Iron Overload (cont.)

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

How is hereditary hemachromatosis inherited?

Hereditary hemochromatosis is an autosomal recessive disorder, which means an individual has the possibility of developing iron overload only when a pair of abnormal genes are inherited from both parents. (An autosomal recessive disorder is different from autosomal dominant disorder in which individuals can develop disease by inheriting a single abnormal gene from only one parent.)

The human body is composed of trillions of cells. Inside the inner core (nucleus) of each cell are chromosomes. Every human cell has two sets of 23 chromosomes (total of 46 chromosomes). Each set is inherited from one parent. Chromosomes contain DNA that carries genes that govern all bodily functions including cell metabolism, appearance, height, intelligence, hair and eye color, and other physical traits. Defects in DNA (also called mutations) are passed from one generation to the next, and sometimes can cause diseases.

There are primarily two mutations associated with hereditary hemochromatosis; C282Y and H63D. The numbers 282 and 63 designate the location of the defects on the HFE gene located on chromosome number 6. An individual who inherits two C282Y mutations (one from each parent) is called a C282Y homozygote, and has a significant chance of developing hemochromatosis. In fact, C282Y homozygotes account for the majority of cases of hereditary hemochromatosis. Patients who inherit one C282Y mutation from one parent and another H63D mutation from another parent are called compound heterozygotes, accounting for a small number of the cases of hereditary hemochromatosis.